Acryl is a type I receptor for bone morphogenic proteins (BMPs). Certain mutations in the human Acvr1 gene, including mutations that give rise to the amino acid modification R206H mutation, are strongly associated with the disease fibrodysplasia ossificans progressiva (FOP) (see, e.g., US Pat. Appl. Publ. No. 2009/0253132; see also, Pignolo, R. J. (2011) Fibrodysplasia Ossificans Progressiva: Clinical and Genetic Aspects, Orphanet Journal of Rare Diseases, 6:80, 1-6). The R206H mutation, among others, is believed to increase sensitivity of the receptor to activation and render it more resistant to silencing. Chimeric mice that bear an R206H mutation in Acvr1 develop an FOP-like phenotype (see, e.g., Chakkalakal et al. (2012) An Acvr1 R206H knock-in mouse has fibrodysplasia ossificans progressiva, J. Bone and Mineral Res. 27:1746-1756).
Certain mutations in the Acvr1, e.g., those resulting in an R206H Acvr1 protein mutation, are perinatal lethal in mice. Where a mutation is perinatal lethal, it is not possible to pass a knock-in gene comprising the mutation through the germline of a non-human animal. For example, the above-mentioned studies required working with chimeric mice that possess in some cells the indicated mutation but that are unable to transmit the mutation in the germline; thus, a stable and useful mouse line has not been established that comprises the R206H mutation in the germline. There remains a need for non-human animals that can transmit an ACRV1 mutation that is perinatal or embryonic lethal in the germline to produce progeny that are useful, e.g., to produce a non-human animal that exhibits a phenotype associated with the ACRV1 mutation, e.g. FOP, an FOP feature, or a feature of a related disorder, or a related disorder.